Hibernate：视图映射

于 2013-09-30 17:39:00 发布
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文章标签： java 数据库 开发工具
本文介绍如何使用Hibernate映射跨数据库视图，包括创建视图、生成POJO类及配置文件的过程。针对视图无主键的问题提出了解决方案。

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虽然Hibernate提供的HQL可以实现多表联合查询，但是我们一般都是将多表查询直接创建为一个视图，直接查询视图就可以了。那么Hibernate怎样映射视图呢？

在网上找了一篇较实用的文章现分享给大家。

文章链接：http://blog.youkuaiyun.com/kingkuang2006/article/details/6981974


由于项目（ssh）有需求根据关键字查询位于同一服务器下不同数据库的2张表t_navi和t_news，由于涉及到分页查询，故不想自己手动去写sql语句来实现跨表查询，不但麻烦而且容易写错，所以想用Hibernate视图来完成该功能，因此上网查看了一些资料，并最终完美解决，故将解决方案记录如下：

一、首先创建一个跨数据库视图

mysql>create view db_cms.search_view as(select * from db_cms.t_navi)union all(select* from db_news.t_news);

注：由于t_navi 和 t_news两张表字段数量和意义完全相同，所以这里使用了union all；

二、生成POJO类和Hibernate配置文件

如果怕自己容易写错，可以使用Myeclipse通过视图反向生成POJO类和**.hbm.xml,如果通过Myeclipse生成的话，将生成如下几个文件：

SearchView.java SearchViewId.java SearchView.hbm.xml

1、SearchView.java

[java] view plain copy print ?
  1. publicclassSearchViewimplementsSerializable{
  2. /**
  3. *
  4. */
  5. privatestaticfinallongserialVersionUID=-1372050399492830775L;
  6. privateSearchViewIdid;
  8. publicSearchViewIdgetId(){
  9. returnid;
  10. }
  12. publicvoidsetId(SearchViewIdid){
  13. this.id=id;
  14. }
  15. }

2、SearchViewId.java

[java] view plain copy print ?
  1. publicclassSearchViewIdimplementsSerializable{
  2. privatestaticfinallongserialVersionUID=-2960868353091674237L;
  3. privateIntegerid;
  4. privateStringnaviTitle;
  5. privateBooleannaviShow=true;
  6. privateBooleantreeShow=true;
  7. privateBooleanjumpHref=false;
  8. privateBooleanwindowOpen=false;
  9. privateIntegerauditStatus;
  10. privateDatecreateDate;
  11. privateDateupdateDate;
  12. privateStringcontent;
  13. privateStringaccessPath;
  14. privateStringjumpHrefUrl;
  16. publicIntegergetId(){
  17. returnid;
  18. }
  20. publicvoidsetId(Integerid){
  21. this.id=id;
  22. }
  24. publicStringgetNaviTitle(){
  25. returnnaviTitle;
  26. }
  28. publicvoidsetNaviTitle(StringnaviTitle){
  29. this.naviTitle=naviTitle;
  30. }
  32. publicBooleangetNaviShow(){
  33. returnnaviShow;
  34. }
  36. publicvoidsetNaviShow(BooleannaviShow){
  37. this.naviShow=naviShow;
  38. }
  40. publicBooleangetTreeShow(){
  41. returntreeShow;
  42. }
  44. publicvoidsetTreeShow(BooleantreeShow){
  45. this.treeShow=treeShow;
  46. }
  48. publicBooleangetJumpHref(){
  49. returnjumpHref;
  50. }
  52. publicvoidsetJumpHref(BooleanjumpHref){
  53. this.jumpHref=jumpHref;
  54. }
  56. publicBooleangetWindowOpen(){
  57. returnwindowOpen;
  58. }
  60. publicvoidsetWindowOpen(BooleanwindowOpen){
  61. this.windowOpen=windowOpen;
  62. }
  64. publicIntegergetAuditStatus(){
  65. returnauditStatus;
  66. }
  68. publicvoidsetAuditStatus(IntegerauditStatus){
  69. this.auditStatus=auditStatus;
  70. }
  72. publicDategetCreateDate(){
  73. returncreateDate;
  74. }
  76. publicvoidsetCreateDate(DatecreateDate){
  77. this.createDate=createDate;
  78. }
  80. publicDategetUpdateDate(){
  81. returnupdateDate;
  82. }
  84. publicvoidsetUpdateDate(DateupdateDate){
  85. this.updateDate=updateDate;
  86. }
  88. publicStringgetContent(){
  89. returncontent;
  90. }
  92. publicvoidsetContent(Stringcontent){
  93. this.content=content;
  94. }
  96. publicStringgetAccessPath(){
  97. returnaccessPath;
  98. }
  100. publicvoidsetAccessPath(StringaccessPath){
  101. this.accessPath=accessPath;
  102. }
  104. publicStringgetJumpHrefUrl(){
  105. returnjumpHrefUrl;
  106. }
  108. publicvoidsetJumpHrefUrl(StringjumpHrefUrl){
  109. this.jumpHrefUrl=jumpHrefUrl;
  110. }
  111. }

3、SearchView.hbm.xml

[java] view plain copy print ?
  1. <?xmlversion="1.0"encoding="UTF-8"?>
  2. <!DOCTYPEhibernate-mappingPUBLIC"-//Hibernate/HibernateMappingDTD3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
  4. <hibernate-mappingpackage="org.bgi.cms.domain">
  5. <classname="SearchView"table="search_view">
  6. <spanstyle="color:#ff0000;"><composite-idname="id"class="SearchViewId">
  7. </span><key-propertyname="id"type="integer">
  8. <columnname="id"/>
  9. </key-property>
  10. <key-propertyname="naviTitle"type="string">
  11. <columnname="navi_title"length="255"/>
  12. </key-property>
  13. <key-propertyname="naviShow"type="yes_no">
  14. <columnname="is_navi_show"/>
  15. </key-property>
  16. <key-propertyname="treeShow"type="yes_no">
  17. <columnname="is_tree_show"/>
  18. </key-property>
  19. <key-propertyname="jumpHref"type="yes_no">
  20. <columnname="is_jump_href"/>
  21. </key-property>
  22. <key-propertyname="windowOpen"type="yes_no">
  23. <columnname="is_window_open"/>
  24. </key-property>
  25. <key-propertyname="auditStatus"type="integer">
  26. <columnname="audit_status"/>
  27. </key-property>
  28. <key-propertyname="createDate"type="timestamp">
  29. <columnname="create_date"/>
  30. </key-property>
  31. <key-propertyname="updateDate"type="timestamp">
  32. <columnname="update_date"/>
  33. </key-property>
  34. <key-propertyname="content"type="text">
  35. <columnname="content"/>
  36. </key-property>
  37. <key-propertyname="jumpHrefUrl"type="string">
  38. <columnname="jump_href_url"length="255"/>
  39. </key-property>
  40. <key-propertyname="accessPath"type="string">
  41. <columnname="access_path"length="45"/>
  42. </key-property>
  43. <spanstyle="color:#ff0000;"></composite-id>
  44. </span></class>
  45. </hibernate-mapping>

注：由于视图是没有主键的，所以Myeclipse生成的hbm.xml配置文件会将所有字段放在一起当做联合主键，这样做有一个问题就是，一旦视图中某个字段为null的话，该条数据在做查询时是查不出来的，所以现在暂时还不能完全确定可以使用该配置文件（如果这些联合主键中的所有字段都是不能为空的话就没有问题，完全可以放心的使用工具生成的改配置文件），因为在我的项目中，视图中的content、jumpHrefUrl以及accessPath字段都是可以为空的，所以需要修改这3个文件，如下：

1、SearchView.java（红色的为修改的）

[java] view plain copy print ?
  1. publicclassSearchViewimplementsSerializable{
  2. /**
  3. *
  4. */
  5. privatestaticfinallongserialVersionUID=-1372050399492830775L;
  6. privateSearchViewIdid;
  8. <spanstyle="color:#ff0000;">privateStringcontent;
  9. privateStringaccessPath;
  10. privateStringjumpHrefUrl;
  11. </span>
  12. publicSearchViewIdgetId(){
  13. returnid;
  14. }
  16. publicvoidsetId(SearchViewIdid){
  17. this.id=id;
  18. }
  20. <spanstyle="color:#ff0000;">publicStringgetContent(){
  21. returncontent;
  22. }
  24. publicvoidsetContent(Stringcontent){
  25. this.content=content;
  26. }
  28. publicStringgetAccessPath(){
  29. returnaccessPath;
  30. }
  32. publicvoidsetAccessPath(StringaccessPath){
  33. this.accessPath=accessPath;
  34. }
  36. publicStringgetJumpHrefUrl(){
  37. returnjumpHrefUrl;
  38. }
  40. publicvoidsetJumpHrefUrl(StringjumpHrefUrl){
  41. this.jumpHrefUrl=jumpHrefUrl;
  42. }
  43. </span>}
2、 SearchViewId.java（红色的为修改的 ）
[java] view plain copy print ?
  1. publicclassSearchViewIdimplementsSerializable{
  2. privatestaticfinallongserialVersionUID=-2960868353091674237L;
  3. privateIntegerid;
  4. privateStringnaviTitle;
  5. privateBooleannaviShow=true;
  6. privateBooleantreeShow=true;
  7. privateBooleanjumpHref=false;
  8. privateBooleanwindowOpen=false;
  9. privateIntegerauditStatus;
  10. privateDatecreateDate;
  11. privateDateupdateDate;
  13. <spanstyle="color:#ff0000;">//privateStringcontent;
  14. //privateStringaccessPath;
  15. //privateStringjumpHrefUrl;
  16. </span>
  17. publicIntegergetId(){
  18. returnid;
  19. }
  21. publicvoidsetId(Integerid){
  22. this.id=id;
  23. }
  25. publicStringgetNaviTitle(){
  26. returnnaviTitle;
  27. }
  29. publicvoidsetNaviTitle(StringnaviTitle){
  30. this.naviTitle=naviTitle;
  31. }
  33. publicBooleangetNaviShow(){
  34. returnnaviShow;
  35. }
  37. publicvoidsetNaviShow(BooleannaviShow){
  38. this.naviShow=naviShow;
  39. }
  41. publicBooleangetTreeShow(){
  42. returntreeShow;
  43. }
  45. publicvoidsetTreeShow(BooleantreeShow){
  46. this.treeShow=treeShow;
  47. }
  49. publicBooleangetJumpHref(){
  50. returnjumpHref;
  51. }
  53. publicvoidsetJumpHref(BooleanjumpHref){
  54. this.jumpHref=jumpHref;
  55. }
  57. publicBooleangetWindowOpen(){
  58. returnwindowOpen;
  59. }
  61. publicvoidsetWindowOpen(BooleanwindowOpen){
  62. this.windowOpen=windowOpen;
  63. }
  65. publicIntegergetAuditStatus(){
  66. returnauditStatus;
  67. }
  69. publicvoidsetAuditStatus(IntegerauditStatus){
  70. this.auditStatus=auditStatus;
  71. }
  73. publicDategetCreateDate(){
  74. returncreateDate;
  75. }
  77. publicvoidsetCreateDate(DatecreateDate){
  78. this.createDate=createDate;
  79. }
  81. publicDategetUpdateDate(){
  82. returnupdateDate;
  83. }
  85. publicvoidsetUpdateDate(DateupdateDate){
  86. this.updateDate=updateDate;
  87. }
  89. <spanstyle="color:#ff0000;">//</span><spanstyle="color:#ff0000;">publicStringgetContent(){
  90. //returncontent;
  91. //}
  92. //
  93. //publicvoidsetContent(Stringcontent){
  94. //this.content=content;
  95. //}
  96. //
  97. //publicStringgetAccessPath(){
  98. //returnaccessPath;
  99. //}
  100. //
  101. //publicvoidsetAccessPath(StringaccessPath){
  102. //this.accessPath=accessPath;
  103. //}
  104. //
  105. //publicStringgetJumpHrefUrl(){
  106. //returnjumpHrefUrl;
  107. //}
  108. //
  109. //publicvoidsetJumpHrefUrl(StringjumpHrefUrl){
  110. //this.jumpHrefUrl=jumpHrefUrl;
  111. //}
  112. </span>}
3、 SearchView.hbm.xml（红色的为修改的）
[java] view plain copy print ?
  1. <?xmlversion="1.0"encoding="UTF-8"?>
  2. <!DOCTYPEhibernate-mappingPUBLIC"-//Hibernate/HibernateMappingDTD3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
  4. <hibernate-mappingpackage="org.bgi.cms.domain">
  5. <classname="SearchView"table="search_view">
  6. <composite-idname="id"class="SearchViewId">
  7. <key-propertyname="id"type="integer">
  8. <columnname="id"/>
  9. </key-property>
  10. <key-propertyname="naviTitle"type="string">
  11. <columnname="navi_title"length="255"/>
  12. </key-property>
  13. <key-propertyname="naviShow"type="yes_no">
  14. <columnname="is_navi_show"/>
  15. </key-property>
  16. <key-propertyname="treeShow"type="yes_no">
  17. <columnname="is_tree_show"/>
  18. </key-property>
  19. <key-propertyname="jumpHref"type="yes_no">
  20. <columnname="is_jump_href"/>
  21. </key-property>
  22. <key-propertyname="windowOpen"type="yes_no">
  23. <columnname="is_window_open"/>
  24. </key-property>
  25. <key-propertyname="auditStatus"type="integer">
  26. <columnname="audit_status"/>
  27. </key-property>
  28. <key-propertyname="createDate"type="timestamp">
  29. <columnname="create_date"/>
  30. </key-property>
  31. <key-propertyname="updateDate"type="timestamp">
  32. <columnname="update_date"/>
  33. </key-property>
  34. </composite-id>
  35. <spanstyle="color:#ff0000;"><propertyname="content"column="content"type="text"/>
  36. <propertyname="jumpHrefUrl"column="jump_href_url"type="string"length="255"/>
  37. <propertyname="accessPath"column="access_path"type="string"length="45"/>
  38. </span></class>
  39. </hibernate-mapping>
iteye_19583
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